RECENT ADDITIONS TO OUR KNOWLEDGE 

 OF THE ANCIENT SEDIMENTS. 



SINCE the publication of the map and writings of 

 William Smith there have been two particularly im- 

 portant events in the progress of our study of the older 

 sediments, the first being the elucidation of the structure 

 of North Wales and the Welsh borderland by Murchison 

 and Sedgwick, and the second the publication of Lapworth's 

 memoir on the Moffat series (i). 1 



Lapworth's paper marked the commencement of a new 

 era in the study of our ancient sediments, and, as it exer- 

 cised a profound influence upon the work which has been 

 achieved in recent times, it will be convenient to take it as 

 our starting-point, when attempting a sketch of the progress 

 of our knowledge of the older rocks during the last few 

 years. This progress has been made in two ways : firstly, 

 by furnishing us with more accurate information of the 

 methods of stratigraphical geology, and, secondly, by ena- 

 bling us to apply our knowledge of the strata to the elucidation 

 of geological problems with greater success. In giving a 

 brief outline of recent advance, I propose to dwell, in the 

 first instance, upon the methods of stratigraphical geology, 

 and afterwards upon the application of knowledge thus 

 acquired. 



METHODS OF STRATIGRAPHICAL GEOLOGY. 



The recent work which has borne most fruit is due to 

 a more detailed application of Smith's principle of strata 

 being identifiable by their organised fossils — a principle 

 which, until the publication of Lapworth's work on the 

 Moffat series, had been viewed somewhat askance, owing 

 in great part to the publication of the theoretical views of 

 Whewell, Huxley and Spencer, which were readily adopted 



1 The numbers refer to the list of papers appended to this article. 



